Problem pairing GTX 275 w/ GTX 470

[AbnRanger]

A few weeks ago, I had no problem getting RT 2 to work with the GTX 470, but as soon as I added a GTX 275 into the mix, RT would just never work in GPU mode. I had no problem with the NVidia drivers using each card in a dual monitor config, but getting RT to work with both was a fruitless effort.

Both were recognized and enabled by RT GPU, but no dice. The only way to get RT GPU to work was remove one of the cards. I figured it must have had something to do with one card being a 200x series and the other a Fermi card.

Any confirmation on your end, Vlado, that this combo will not work?

[vlado]

It will not work at present; all cards need to be of the same architecture (Fermi- or not). There is a way around it (we could compile the GPU code separately for each card) and we'll try to do that for the next releases. Right now V-Ray compiles the GPU code for one card, and tries to use it on all cards, which won't work if they have different architectures.

Best regards,
Vlado

[vlado]

Forgot to mention; it is not necessary to remove one card - just disable from the V-Ray RT device selector in the Start menu.

Best regards,
Vlado

[AbnRanger]

When I tried that, it still didn't work. I took the 275 out and re-installed the latest NVidia driver for the 470, and RT GPU finally started working as advertised. I saw you asked about the 580 on the Max thread at CG Talk. So, does that "hamstringing" by NVidia hamper the Fermi cards for RT? I mean should I use the 275 instead?

[vlado]

When you disable the 275 card, make sure you also delete the .clbin file in your temporary folder, so that V-Ray can compile the code for the 470 card directly.

Best regards,
Vlado

[AbnRanger]

Thanks....that helpful to know.